Surgical loading unit including an articulating end effector

ABSTRACT

A surgical loading unit includes an elongate body, an end effector pivotably coupled to the elongate body, and a flexible knife bar extending through a distal portion of the elongate body and a proximal portion of the end effector. Articulation of the end effector relative to the elongate body in a first direction moves a first segment of the knife bar in the first direction and moves a second segment of the knife bar in a second direction, opposite the first direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patent application Ser. No. 15/945,404, filed on Apr. 4, 2018, which claims the benefit of and priority to U.S. Provisional Application No. 62/500,259, filed on May 2, 2017, the entire contents of each of which are incorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates generally to surgical loading units for endoscopic use and, more specifically, to surgical loading units having articulation assemblies for articulating an end effector of the surgical loading unit.

Background of Related Art

Various types of surgical instruments used to endoscopically treat tissue are known in the art, and are commonly used, for example, for closure of tissue or organs in transection, resection, anastomoses, for occlusion of organs in thoracic and abdominal procedures, and for electrosurgically fusing or sealing tissue.

One example of such a surgical instrument is a surgical stapling instrument. Typically, surgical stapling instruments include an end effector having an anvil assembly and a cartridge assembly for supporting an array of surgical staples, an approximation mechanism for approximating the cartridge and anvil assemblies, and a firing mechanism for ejecting the surgical staples from the cartridge assembly.

During laparoscopic or endoscopic surgical procedures, access to a surgical site is achieved through a small incision or through a narrow cannula inserted through a small entrance wound in a patient. Because of limited area available to access the surgical site, many endoscopic instruments include mechanisms for articulating the end effector of the instrument in relation to a body portion of the instrument to improve access to tissue to be treated. In addition, some end effectors have a knife blade that translates therethrough to tissue grasped by jaws of the end effector. During articulation of the end effector, the knife blade experiences a bending moment and/or a shear force that may degrade the knife blade over continued articulation of the end effector.

Accordingly, it would be beneficial to provide an improved surgical instrument, which includes a mechanism for articulating the end effector relative to the body portion in a variety of orientations without damaging a knife blade that moves through the end effector.

SUMMARY

In one aspect of the present disclosure, a surgical loading unit is provided that includes an elongate body, an end effector having a proximal portion pivotably coupled to a distal portion of the elongate body, and a knife assembly disposed within the elongate body. The knife assembly includes an elongate guide member and a flexible knife bar. The elongate guide member is pivotably supported in the distal portion of the elongate body. The knife bar is configured to move through a longitudinally-extending channel defined through the elongate guide member. Articulation of the end effector relative to the elongate body in a first direction effects movement of a distal portion of the elongate guide member in a second direction, opposite the first direction.

In some embodiments, the elongate body may define a first longitudinal axis and the end effector may define a second longitudinal axis. The end effector may be configured to move relative to the elongate body from a first position in which the second longitudinal axis is aligned with the first longitudinal axis to a second position in which the second longitudinal axis is misaligned with the first longitudinal axis. Upon the end effector moving to the second position, a distal portion of the end effector may be disposed on a first side of a central longitudinal axis defined by the elongate body and the distal portion of the elongate guide member of the knife assembly may be disposed on a second side of the central longitudinal axis defined by the elongate body.

It is contemplated that the knife bar may be more flexible than the elongate guide member such that the elongate guide member is configured to maintain a linear shape as a segment of the knife bar that is located distally of the elongate guide member flexes during articulation of the end effector.

It is envisioned that the knife assembly may further include a pair of blow-out plates extending along opposite sides of the knife bar. The pair of blow-out plates may have a distal portion coupled to the proximal portion of the end effector. A first blow-out plate may have a proximal portion disposed between a first lateral side of the knife bar and a first lateral side of the elongate guide member, and a second blow-out plate may have a proximal portion disposed between a second lateral side of the knife bar and a second lateral side of the elongate guide member. The proximal portion of the first blow-out plate may be configured to slide relative to the elongate guide member in a first axial direction, and the proximal portion of the second blow-out plate may be configured to slide relative to the elongate guide member in a second axial direction in response to the end effector articulating.

In some embodiments, the proximal portion of the end effector may include first and second walls that taper proximally such that the first and second walls cooperatively define a proximally-flaring cavity through which both the distal portion of the knife bar and the pair of blow-out plates extend. Each of the first and second walls may define arcuate side surfaces that are laterally spaced from one another. The arcuate side surface of the first wall may be configured to contact the first blow-out plate when the end effector articulates in the first direction, and the arcuate side surface of the second wall may be configured to contact the second blow-out plate when the end effector articulates in the second direction.

It is contemplated that a proximal portion of the first wall may be configured to contact the first blow-out plate in response to an articulation of the end effector in the first direction to move the distal portion of the elongate guide member in the second direction. The proximal portion of the second wall may be configured to contact the second blow-out plate in response to an articulation of the end effector in the second direction to move the distal portion of the elongate guide member in the first direction.

It is envisioned that a proximal portion of the first wall may be configured to move the distal portion of the elongate guide member in the second direction in response to an articulation of the end effector in the first direction, and a proximal portion of the second wall may be configured to move the distal portion of the elongate guide member in the first direction in response to an articulation of the end effector in the second direction.

In some embodiments, the elongate guide member may include a proximal portion pivotably coupled to the elongate body. The proximal portion of the elongate guide member may have a circular tab pivotably coupled to the elongate body, such that the elongate guide member is prevented from translating longitudinally relative to the elongate body.

It is contemplated that the knife assembly may further include a track defining a longitudinally-extending channel. The flexible knife bar may include a first knife bar shaft and a second knife bar shaft coupled to and extending parallel with the first knife bar shaft. The first knife bar shaft may extend through the channel of the elongate guide member. The second knife bar shaft may extend through the channel of the track.

It is envisioned that the track and the elongate guide member may be less flexible than the knife bar, such that the track and the elongate guide member are configured to maintain a linear shape during articulation of the end effector relative to the elongate body.

In some embodiments, the surgical loading unit may further include a support structure disposed between the first and second knife bar shafts of the flexible knife bar. The support structure may include a top surface on which the elongate guide member is supported, and a bottom surface on which the track is supported.

In some aspects, the elongate body may include a support structure on which the knife assembly is supported. The support structure may have a distal portion pivotably coupled to the proximal portion of the end effector. The support structure may have a planar top surface that defines a distally-flaring cavity therein. The elongate guide member may be disposed within the distally-flaring cavity.

It is contemplated that the elongate body may include an articulation assembly for effecting articulation of the end effector. The articulation assembly may include an elongated drive nut extending through a proximal portion of the support structure, an elongated drive screw extending through a distal portion of the support structure and having a proximal portion threadingly coupled to the drive nut, and an articulation link having a proximal portion pivotably coupled to a distal portion of the drive screw, and a distal portion pivotably coupled to the proximal portion of the end effector. Rotation of the drive nut may axially move the drive screw to pivot the articulation link and, in turn, articulate the end effector.

It is envisioned that the articulation assembly may be laterally offset from a central longitudinal axis defined by the elongate body.

In some embodiments, the knife bar may have a proximal portion operably coupled to an actuator for axially moving the knife bar through the elongate body, and a distal portion that supports a knife blade for cutting tissue. The end effector may include a staple cartridge and an anvil. The staple cartridge may define a longitudinally-extending channel dimensioned for slidable receipt of the knife blade.

In another aspect of the present disclosure, a surgical loading unit is provided that includes an elongate body, an end effector having a proximal portion pivotably coupled to a distal portion of the elongate body, and a flexible knife bar extending through the distal portion of the elongate body and the proximal portion of the end effector. Articulation of the end effector relative to the elongate body in a first direction may curve a first segment of the knife bar in the first direction and may pivot a second segment of the knife bar in a second direction, opposite the first direction, while the second segment maintains a linear shape. The second segment may be disposed proximally of the first segment.

BRIEF DESCRIPTION OF THE DRAWINGS

Surgical loading units including embodiments of the presently disclosed articulation mechanism are disclosed herein with reference to the drawings, wherein:

FIG. 1A is a perspective view of a surgical stapling instrument in accordance with the present disclosure;

FIG. 1B is a perspective view of another surgical stapling instrument in accordance with the present disclosure, shown in a non-articulated or linear position;

FIG. 2A is a perspective view of a distal end portion of a surgical loading unit for use with the surgical stapling instruments of FIGS. 1A and 1B;

FIG. 2B is a top view of the loading unit of FIG. 2A;

FIG. 2C is a first side view of the loading unit of FIG. 2A;

FIG. 2D is a second side view of the loading unit of FIG. 2A;

FIG. 3 is a perspective view, with an outer housing removed, of the loading unit of FIG. 2A illustrating an articulation mechanism and a knife assembly thereof;

FIG. 4 is an enlarged view, with the outer housing and an inner housing removed, of the surgical loading unit of FIG. 3;

FIG. 5 is a perspective cross-sectional view, taken along line 5-5 in FIG. 4, of the loading unit illustrating the articulation mechanism;

FIG. 6A is a top view of the cross-section of FIG. 5 illustrating the loading unit in a non-articulated position, with an end effector of the loading unit axially aligned with an elongate body of the loading unit;

FIG. 6B is a top view of the cross-section of FIG. 5 illustrating the end effector of the loading unit in a first articulated position relative to the elongate body of the loading unit;

FIG. 6C is a top view of the cross-section of FIG. 5 illustrating the end effector of the loading unit in a second articulated position relative to the elongate body of the loading unit;

FIG. 7 is a perspective view, with the outer housing of the elongate body removed, of the surgical loading unit illustrating the knife assembly of the loading unit;

FIG. 8 is a top, perspective view, with the inner and outer housings of the elongate body removed, of the surgical loading unit of FIG. 7 further illustrating the knife assembly;

FIG. 9 is an enlarged view of the indicated area of detail of FIG. 8;

FIG. 10 is an enlarged view of a knife bar, blow-out plates, and a knife bar track of the knife assembly of FIG. 9;

FIG. 11 is a top, perspective view, with parts removed, of the surgical loading unit of FIG. 9 illustrating the end effector in an articulated position;

FIG. 12 is a side view of the surgical loading unit of FIG. 11 illustrating the end effector in the articulated position;

FIG. 13A is a side view of the surgical loading unit illustrating a staple cartridge and an anvil of the end effector in an open position; and

FIG. 13B is a cross-section, taken along line 13B-13B, of the end effector of FIG. 13A, illustrating the staple cartridge and the anvil in an approximated configuration.

DETAILED DESCRIPTION

Persons skilled in the art will understand that the loading units and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of the present disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims.

As used herein, the term “distal” refers to that portion of the surgical instrument or loading unit which is farthest from a clinician, while the term “proximal” refers to that portion of the surgical instrument or loading unit which is closest to the clinician. In addition, as used herein, the term clinician refers to medical staff including doctors, nurses and support personnel.

The present disclosure is directed to a knife assembly for use in an articulating surgical loading unit or surgical instrument. The knife assembly includes a flexible knife bar supported on either side by a knife bar guide. The knife assembly is configured such that upon articulation of an end effector of the loading unit relative to an elongate body of the loading unit, the knife bar of the knife assembly bends in the direction of articulation while also shifting in a direction away from the direction of articulation. The knife bar shifting or pivoting in a substantially opposite direction from which the knife bar is being bent causes the knife bar to assume a larger radius of curvature during articulation of the end effector. Bending along a larger radius of curvature prolongs the life of the knife bar by reducing shear forces and/or bending moments experienced by the knife bar while also providing a greater articulation angle of the end effector.

The present disclosure further provides an articulation assembly for articulating an end effector of a loading unit relative to an elongate body of the loading unit. The articulation assembly includes an elongate drive unit and an elongate drive screw operably coupled to one another and each being disposed toward a distal end of the elongate body, as will described in further detail below.

Additional advantages of the presently disclosed knife assembly, articulation assembly, and surgical loading units including the presently disclosed knife assembly and articulation assembly are described below.

FIGS. 1A and 1B illustrate surgical stapling instruments for use with surgical loading units incorporating embodiments of the presently disclosed articulation assembly 130 and knife assembly 160, referenced generally as surgical stapling instruments 10 a and 10 b. Each of the surgical stapling instruments 10 a and 10 b can be used with the same surgical loading unit 100. While the depicted surgical stapling instruments 10 a, 10 b fire staples, it is contemplated that the surgical loading unit 100 may be adapted to fire any other suitable fastener such as clips and two-part fasteners. Additionally, while the figures depict a linear surgical stapling instrument, it is envisioned that the presently disclosed articulation assembly and knife assembly are suitable for use with other types of endoscopic surgical instruments including non-linear surgical stapler loading units, endoscopic forceps, graspers, dissectors, other types of surgical stapling instruments, powered vessel sealing and/or cutting devices, etc.

Generally, with reference to FIG. 1A, the surgical instrument 10 a includes a handle assembly 12 including a movable handle 14, an adapter assembly 16 extending from the handle assembly 12, and a surgical loading unit 100 coupled to a distal end portion of an outer tube 18 of the adapter assembly 16. As known in the art, the movable handle 14 is actuatable (e.g., through one or more strokes) to cause distal advancement of a drive rod (not shown), such that the drive rod engages a portion of a drive assembly (not shown), which forces at least a portion of the drive assembly to translate distally, thereby firing staples from the surgical loading unit 100. Further details of how actuation of the movable handle 14 causes distal advancement of the drive rod are explained in U.S. Pat. No. 6,953,139 to Milliman et al., the entire contents of which are incorporated by reference herein.

Generally, with reference to FIG. 1B, the surgical instrument 10 b is a motor-driven electromechanical device that includes a handle assembly 20 including a control or button 22, an adapter assembly 24 coupled to the handle assembly 20, and the surgical loading unit 100 disposed adjacent a distal portion 32 of an outer tube 30 of the adapter assembly 24. The adapter assembly 24 includes an outer knob housing 26 coupled to a distal end portion of the handle assembly 20, and the outer tube 30 of the adapter assembly 24 extends from a distal end portion of the knob housing 26. The button 22 of the handle assembly 20 is in electrical communication with a motorized drive shaft (not shown), which is operatively coupled to an articulation assembly 130 of the loading unit 100 such that actuation of the actuation button 22 causes the articulation mechanism 130 to articulate an end effector 110 of the loading unit 100, as will be described in further detail below.

A detailed description of the various components of the handle assembly 20 and the adapter assembly 24 of surgical instrument 10 b may be found, for example, in U.S. patent application Ser. No. 14/550,071 (now U.S. Patent Application Publication No. 2015/0157320), the entire contents of which being incorporated by reference herein.

The loading unit 100 is adapted to be attached to the outer tube 30 of the adapter assembly 24 of the surgical stapling instrument 10 b (or the outer tube 18 of the adapter assembly 16 of surgical stapling instrument 10 a). The loading unit 100 may be configured for a single use, or may be configured to be used more than once and includes an elongate body 102 and an end effector 110 supported on a distal portion 102 b of the elongate body 102. In some embodiments, the end effector 110, including a staple cartridge 112 and an anvil 114, may not form part of the loading unit 100, but rather, may be directly pivotably coupled to the distal portion 32 of the outer tube 30 of the adapter assembly 24.

The elongate body 102 of the loading unit 100 defines a first longitudinal axis “X1” and has a proximal portion 102 a removably received within the distal portion 32 of the outer tube 30 of the adapter assembly 24 of the surgical stapling instrument 10 b using, e.g., a bayonet or luer type coupling. The elongate body 102 of the loading unit 100 may include an outer housing or tube 106 (FIG. 2A) and an inner housing or tube 108 disposed within the outer housing 106. In some embodiments, the elongate body 102 of the loading unit 100 may be integrally connected to or monolithically formed with the outer tube 30 of the adapter assembly 24 of the surgical stapling instrument 10 b.

With reference to FIGS. 2A-2D, the end effector 110 of the loading unit 100 defines a second longitudinal axis “X2” that is aligned with the first longitudinal axis “X1” of the elongate body 102 when the end effector 110 is in a non-articulated position (FIGS. 2A-2D and 6A), and is misaligned with the first longitudinal axis “X1” of the elongate body 102 when the end effector 110 is in an articulated position (FIGS. 6B and 6C). The end effector 110 has a proximal portion 110 a pivotably coupled to the distal portion 102 b of the elongate body 102.

In particular, with reference to FIGS. 3-6C, the distal portion 102 b of the elongate body 102 of the loading unit 100 includes a support structure or platform 116 axially fixed within the inner housing 108 of the elongate body 102 (FIG. 3). The support structure 116 has an elongated, planar configuration, but in some embodiments, may assume any suitable configuration, such as tubular, cylindrical, or the like. The support structure 116 of the elongate body 102 has a distally-extending tapered extension 118. The proximal portion 110 a of the end effector 110 includes a pair of flanges 113 a, 113 b extending proximally therefrom. The tapered extension 118 of the support structure 116 is received in the space defined between the pair of flanges 113 a, 113 b of the end effector 110. A pivot pin 120 extends through each of the tapered extension 118 of the support structure 116 of the elongate body 102 and the pair of flanges 113 a, 113 b of the end effector 110 to pivotably connect the end effector 110 to the elongate body 102. In some embodiments, other pivotable connections between the end effector 110 and the elongate body 102 are contemplated, such as, for example, a ball and socket connection.

With continued reference to FIGS. 3-6C, loading unit 100 includes an articulation assembly 130 that operably interconnects the end effector 110 to the elongate body 102 to facilitate articulation of the end effector 110 relative to the elongate body 102. The presently disclosed articulation assembly 130 is most suitable for use with the powered surgical stapling instrument 10 b of FIG. 1B. However, it is contemplated that the articulation assembly 130 may be modified for use with the manually-operated surgical stapling instrument 10 a of FIG. 1A.

The articulation assembly 130 of the loading unit 100 is laterally offset from a central longitudinal axis “X1” defined by the elongate body 102 and includes an elongated drive nut 132, an elongated drive screw 134 operably coupled to the drive nut 132, and an articulation link 136 operably coupled to the drive screw 134. The drive nut 132 and the drive screw 134 are axially aligned with one another and each extends parallel and laterally offset from the central longitudinal axis “X1” of the elongate body 102. The drive nut 132 extends through a proximal portion 116 a of a longitudinal side 122 of the support structure 116, and the drive screw 134 extends through a distal portion 116 b of the longitudinal side 122 of the support structure 116. The drive nut 132 is rotatably supported and axially fixed in the longitudinal side 122 of the support structure 116, and the drive screw 134 is keyed to the longitudinal side 122 of the support structure 116 to prevent rotation of the drive screw 134 while permitting linear translation of the drive screw 134 relative to the support structure 116.

By positioning the drive nut 132 and the drive screw 134 of the articulation assembly 130 adjacent the distal end of the elongate body 102 of the loading unit 100 rather than the proximal end, the amount of clearance build up that would ordinarily occur in the proximal end of the elongate body 102 is reduced.

The drive nut 132 of the articulation assembly 130 has a proximal portion 132 a operably coupled to the actuation button 22 (FIG. 1B) of the handle assembly 20, and a distal portion 132 b. The drive screw 134 of the articulation assembly 130 has a proximal portion 134 a disposed within the distal portion 132 b of the drive nut 132 and defines external threading operably coupled to internal threading defined in the drive unit 132. As such, rotation of the drive nut 132 relative to and within the support structure 116, in response to an actuation of the button 22 (FIG. 1B), effects linear translation of the drive screw 134 within and relative to the support structure 116.

The articulation link 136 of the articulation assembly 130 has a proximal portion 136 a pivotably coupled to the distal portion 134 b of the drive screw 134, and a distal portion 136 b pivotably coupled to the proximal portion 110 a (e.g., one or both of the flanges 113 a or 113 b) of the end effector 110. The articulation link 136 may have an arcuate configuration, with a convex lateral side oriented toward the pivot axis of the loading unit 100 and a concave side oriented away from the pivot axis. In some embodiments, the articulation link 136 may assume any suitable shape, such as, for example, linear. The articulation link 136 transfers the linear motion of the drive screw 134 into a pivoting motion to articulate the end effector 110 relative to the elongate body 102.

With reference to FIGS. 6A-6C, in use, rotation of the drive nut 132 of the articulation assembly 130 via an actuation of the button 22 (FIG. 1B) linearly translates the drive screw 134 of the articulation assembly 130 in one of a proximal or distal direction based on the direction of rotation of the drive nut 132. For example, as shown in FIG. 6B, a clockwise rotation of the drive nut 132 may result in a distal translation of the drive screw 134 relative to the drive nut 132. As the drive screw 134 translates in a distal direction, indicated by arrow “A” in FIG. 6B, the articulation link 136 of the articulation assembly 130 pivots about the proximal portion 136 a thereof and relative to the distal portion 134 b of the drive screw 134 in a first direction, indicated by arrow “B” in FIG. 6B, due to the end effector 110 being axially fixed relative to the elongate body 102. The articulation link 136 also pivots about the distal portion 136 b thereof relative to the proximal portion 110 a of the end effector 110, which effects articulation of the end effector 110 in the direction “B.”

Similarly, as shown in FIG. 6C, counter-clockwise rotation of the drive nut 132 may result in a proximal translation of the drive screw 134 relative to the drive nut 132. As the drive screw 134 translates in a proximal direction, indicated by arrow “C” in FIG. 6C, the articulation link 136 pivots slightly about the proximal portion 136 a thereof relative to the distal portion 134 b of the drive screw 134. Since the distal portion 136 b of the articulation link 136 is coupled to the end effector 110 at a location offset from the central longitudinal axis “X2” of the end effector 110, the end effector 110 articulates relative to the elongate body 102 in a direction indicated by arrow “D” in FIG. 6C.

With reference to FIGS. 2A-2D, 3, 4, and 7-12, the knife assembly 160 of the loading unit 100 is illustrated. As briefly mentioned above, the knife assembly 160 includes a flexible knife bar 162 that supports a knife blade 164 (FIG. 13B) at a first or distal segment 162 a thereof and bends during the above-described articulation of the end effector 110 relative to the elongate body 102.

With specific reference to FIGS. 7-12, the knife bar 162 of the knife assembly 160 has a second or intermediate segment 162 b extending through the elongate body 102 of the loading unit 100, and a third or proximal segment 162 c operably coupled to a knife bar pusher 166 to couple the knife bar 162 to the button 22 (FIG. 1B) of the handle assembly 20, or to another actuation button of the handle assembly 20, e.g., an actuation button 23. The knife blade 164 (FIG. 13B) is coupled to or monolithically formed with the distal segment 162 a of the knife bar 162. As such, an actuation of the button 23 distally translates the knife bar 162 and the associated knife blade 164 through the end effector 110 to cut tissue grasped by the end effector 110. The knife bar 162 is bifurcated along its length to define a pair of longitudinally-extending knife bar shafts 168 a, 168 b (FIG. 12) having the support structure 116 of the elongate body 102 disposed therebetween.

The knife assembly 160 further includes an elongate guide member or track 170 that supports the intermediate or second segment 162 b of the knife bar 162. The track 170 is supported on a top side 117 a of the support structure 116 and in the inner housing 108 (FIG. 3) of the elongate body 102 of the loading unit 100. The track 170 of the knife assembly 160 has a linear, rectangular shape and defines a longitudinally-extending channel 172 having the intermediate segment 162 b of the knife bar 162 slidably supported therein. In embodiments, the track 170 may assume a variety of suitable shapes, such as, for example, tubular.

The track 170 includes a bottom wall 172 on which the intermediate segment 162 b of the knife bar 162 is supported, and a pair of parallel side walls 174, 176 extending perpendicularly from the bottom wall 172. The pair of side walls 174, 176 extend along and support respective lateral sides 178 a, 178 b of the intermediate segment 162 b of the knife bar 162 such that the track 170 at least partially surrounds the intermediate segment 162 b of the knife bar 162. The track 170 is fabricated from a material that gives the track 170 axial stiffness, such as polyamide-imide or polyether ether ketone. The track 170 has a greater stiffness (e.g., less flexibility) than the flexible knife bar 162. Due to the track 170 having a greater axial stiffness than the knife bar 162, the track 170 resists bending along its length during articulation of the end effector 110 to maintain the linearity of the intermediate segment 162 b of the knife bar 162.

The track 170 of the knife assembly 160 is movably supported on the top side 117 a of the support structure 116 of the elongate body 102. The top side 117 a of the support structure 116 defines a shallow cavity 180 therein. The track 170 is pivotably supported in the cavity 180 of the support structure 116. The cavity 180 defined in the support structure 116 has a proximal portion 180 a and a distally-flaring distal portion 180 b. The distal portion 180 b of the cavity 180 allows for a distal portion 170 b of the track 170 to traverse therein during articulation of the end effector 110, as will be described in detail below. The cavity 180 of the support structure 116 and the track 170 have substantially similar lengths such that the track 170 is prevented from longitudinal translation within the cavity 180 and relative to the support structure 116. In some embodiments, the track 170 may have a circular tab 182 extending from the parallel side walls 174, 176 of the track 170 that pivotably couples to the inner housing 108 (FIG. 3) of the elongate body 102 to allow for rotation of the track 170 relative to the support structure 116, but prevents longitudinal translation of the track 170 relative to the support structure 116.

With continued reference to FIGS. 7-12, the knife assembly 160 further includes blow-out plates or supports 184, 186 that extend along the lateral sides 178 a, 178 b of the knife bar 162, respectively. The blow-out plates 184, 186 are more flexible than the track 170 to allow bending of the plates 184, 186 during articulation of the end effector 110, but are less flexible than the knife bar 162 to prevent buckling of the distal segment 162 a of the knife bar 162 during articulation of the end effector 110.

Each of the blow-out plates 184, 186 has a proximal portion 184 a, 186 a and a distal portion 184 b, 186 b, respectively. The proximal portion 184 a of the first blow-out plate 184 is disposed between the first lateral side 178 a of the knife bar 162 and the first side wall 174 of the track 170. The proximal portion 186 a of the second blow-out plate 186 is disposed between the second lateral side 178 b of the knife bar 162 and the second side wall 176 of the track 170. The proximal portion 184 a, 186 a of each of the blow-out plates 184, 186 are slidably received within the channel 172 of the track 170.

The distal portion 184 b, 186 b of each of the blow-out plates 184, 186 is fixed to the proximal portion 110 a of the end effector 110. In this way, as the end effector 110 articulates relative to the elongate body 102, one of the blow-out plates 184 or 186 will be pulled in a proximal direction and the other of the blow-out plates 184 or 186 will be pushed in a distal direction due to changes in radial distance between the blow-out plates 184, 186 during articulation of the end effector 110. During the pushing and/or pulling of the distal portions 184 b, 186 b of the blow-out plates 184, 186, the proximal portions 184 a, 186 a thereof slide within and relative to the channel 172 of the track 170 and the knife bar 162.

As shown in FIG. 12, the knife assembly 160 has another track 170′ that supports the second knife bar shaft 168 b of the knife bar 162 and another pair of blow-out plates 184′, 186′, each of which are disposed on the bottom side 117 b of the support structure 116. Due to the substantial similarity of the components of the knife assembly 160 disposed on the top side 117 a of the support structure 116 and the components of the knife assembly 160 disposed on the bottom side 117 b of the support structure 116, the components of the knife assembly 160 on the bottom side 117 b of the support structure 116 will not be described.

With continued reference to FIGS. 7-12, the proximal portion 110 a of the end effector 110 of the loading unit 100 cooperates with the knife assembly 160 to facilitate bending of the knife bar 162 of the knife assembly 160 along its axis and a shifting of the knife bar 162 relative to the support structure 116 of the elongate body 102. The proximal portion 110 a of the end effector 110 includes first and second walls 188, 190 that taper in a proximal direction. The walls 188, 190 of the end effector 110 are supported on the top flange 113 a of the end effector 110. As described above, the knife bar 162 is divided into two shafts 168 a, 168 b, thus the proximal portion 110 a of the end effector 110 may have another pair of walls (not explicitly shown) supported on the bottom flange 113 b of the end effector 110 for interacting with the second knife bar shaft 168 b of the knife bar 162. The first and second walls 188, 190 cooperatively define a proximally-flaring cavity 192 through which both the distal segment 162 a of the knife bar 162 and the distal portion 184 b, 186 b of each of the blow-out plates 184, 186 extend. The cavity 192 of the proximal portion 110 a of the end effector 110 accommodates movement of the distal segment 162 a of the knife bar 162 as the knife bar 162 bends with articulation of the end effector 110 in either of the first or second directions.

Each of the first and second walls 188, 190 of the end effector 110 defines an arcuate side surface 194, 196, respectively. The arcuate side surfaces 194, 196 are laterally spaced from one another across the cavity 192 of the proximal portion 110 a of the end effector 110. In some embodiments, the side surfaces 194, 196 of the first and second walls 188, 190 may assume a variety of shapes. The arcuate side surface 194 of the first wall 188 is oriented toward the first lateral side 178 a of the knife bar 162, and the arcuate side surface 196 of the second wall 190 is oriented toward the second lateral side 178 b of the knife bar 162. As will be described in detail below, during articulation of the end effector 110 relative to the elongate body 102, the arcuate side surfaces 194, 196 of the respective first and second walls 188, 190 of the end effector 110 contact the respective blow-out plates 184, 186 to bend the blow-out plates 184, 186 and the distal segment 162 a of the knife bar 162.

In operation, the end effector 110 may be articulated relative to the elongate body 102 in either the first direction, as indicated by arrow “B” in FIGS. 6B and 11, or the second direction, as indicated by arrow “D” in FIG. 6C, via the articulation assembly 130 as described above. During articulation of the end effector 110 of the loading unit 100 in the first direction “B” relative to the elongate body 102, the distal segment 162 a of the knife bar 162 (e.g., the segment of the knife bar 162 that spans each of the distal portion 102 b of the elongate body 102 and the proximal portion 110 a of the end effector 110) bends in the first direction “B.”

Upon the end effector 110 achieving a threshold amount of articulation, the arcuate side surface 194 of the first wall 188 of the end effector 110 contacts the first blow-out plate 184 to urge the distal and intermediate segments 162 a, 162 b of the knife bar 162 in a substantially opposite direction as the first direction “B” (e.g., the direction indicated by arrow “D” in FIG. 11). Further articulation of the end effector 110 in the direction “B” results in a proximal end 193 of the first wall 188 of the end effector 110 to contact the first blow-out plate 184 to further urge the distal and intermediate segments 162 a, 162 b of the knife bar 162 in a substantially opposite direction from the motion of articulation of the end effector 110.

Since the second or intermediate segment 162 b of the knife bar 162 is disposed within the channel 172 of the track 170 of the knife assembly 160, movement or shifting of the knife bar 162 in the direction “D” also causes the track 170 to move or shift in the direction “D.” Due to the proximal portion 170 a of the track 170 being axially fixed relative to the support structure 116, and the distal portion 170 b of the track 170 being free to move, the distal portion 170 b of the track 170 pivots about the proximal portion 170 a thereof.

While the distal segment 162 a of the knife bar 162 is curved during articulation of the end effector 110, the intermediate segment 162 b of the knife bar 162 remains linear because the intermediate segment 162 b of the knife bar 162 extends within the track 170. As the track 170 of the knife assembly 160 pivots in the direction “D,” the distal portion 170 b of the track 170 moves toward a first side of the central longitudinal axis “X1” defined by the elongate body 102 and a distal portion 110 b (FIG. 2B) of the end effector 110 moves toward a second side of the central longitudinal axis “X1” defined by the elongate body 102.

As the track 170 of the knife assembly 160 pivots about the proximal portion 170 a thereof, the knife bar 162 of the knife assembly 160 bends at a point “P” immediately proximal the proximal portion 170 a of the track 170 given the knife bar 162 is disposed outside of the track 170 at the point “P.” While the distal segment 162 a of the knife bar 162 is being bent in the direction “B” during articulation of the end effector 110, the knife bar 162 at the point “P” bends in the direction “D.” In this way, the distal and intermediate segments 162 a, 162 b of the knife bar 162 are shifting or pivoting in an opposite direction from the direction the distal segment 162 a of the knife bar 162 is bending or curving. By moving the distal and intermediate segments 162 a, 162 b of the knife bar 162 in a direction opposite from that of the bending direction of the distal segment 162 a of the knife bar 162, the radius of curvature of the distal segment 162 a of the knife bar 162 is increased. Increasing the radius of curvature of the distal segment 162 a of the knife bar 162 reduces stresses on the knife bar 162 during articulation of the end effector 110 in the direction “B.”

Articulation of the end effector 110 of the loading unit 100 in the opposite direction (e.g., direction “D”) causes a similar phenomenon in the knife bar 162 of the knife assembly 160, but in the opposite directions. In particular, as the end effector 110 is articulated in the second direction “D,” the distal segment 162 a of the knife bar 162 is bent or curved in the second direction “D.” Upon the end effector 110 achieving a threshold amount of articulation, the arcuate side surface 196 of the second wall 190 of the end effector 110 contacts the second blow-out plate 186 of the knife assembly 160 to urge the distal and intermediate segments 162 a, 162 b of the knife bar 162 in a substantially opposite direction as the second direction “D” (e.g., direction “B”.)

Since the intermediate segment 162 b of the knife bar 162 is disposed within the channel 172 of the track 170, movement or shifting of the intermediate segment 162 b of the knife bar 162 in the direction “B” also causes the track 170 to move or pivot in the direction “B.” As the track 170 pivots about the proximal portion 170 a thereof, the knife bar 162 bends at the point “P.” The linear profile of the intermediate segment 162 b of the knife bar 162 is maintained by the track 170 while the knife bar 162 at the point “P” bends in the direction “B.” In this way, the distal segment 162 a of the knife bar 162 is being bent or curved in an opposite direction from the direction the distal and intermediate segments 162 a, 162 b of the knife bar 162 are shifting or moving. By moving the distal and intermediate segments 162 a, 162 b of the knife bar 162 in an opposite direction from that of the bending direction of the distal segment 162 a of the knife bar 162, the radius of curvature of the distal segment 162 a of the knife bar 162 is increased. Increasing the radius of curvature of the distal segment 162 a of the knife bar 162 reduce stresses on the knife bar 162 during articulation of the end effector 110 in the direction “D.”

With reference to FIGS. 13 and 14, the staple cartridge 112 and the anvil 114 of the end effector 110 are illustrated. Each of the staple cartridge 112 and the anvil 114 define longitudinally-extending channels 115 a, 115 b, respectively. A top portion of the knife blade 164 has a laterally-extending projection 164 a slidably captured within the channel 115 b of the anvil 114, and a bottom portion of the knife blade 164 has a laterally-extending projection 164 b slidably captured within the channel 115 a of the staple cartridge 112. The channels 115 a, 115 b support the knife blade 164 therein to stabilize the knife blade 164 during translation of the knife blade 164 through the end effector 110.

The present disclosure also relates to methods of using the described surgical stapling instruments 10 a, 10 b to perform a surgical procedure and/or to articulate an end effector of a surgical stapling loading unit. Staples may be fired from the staple cartridge of the end effector employing a similar mechanism disclosed in U.S. Pat. No. 6,953,139 to Milliman et al., which has been incorporated by reference herein.

Persons skilled in the art will understand that the loading units and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of the present disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. 

What is claimed is:
 1. A surgical loading unit comprising: an elongate body; an end effector having a proximal portion pivotably coupled to a distal portion of the elongate body; and a flexible knife bar extending through the distal portion of the elongate body, the flexible knife bar having a first segment and a second segment, wherein the first segment of the flexible knife bar is configured to curve in a first direction in response to an articulation of the end effector relative to the elongate body in the first direction, and the second segment of the flexible knife bar is configured to pivot in a second direction, opposite the first direction, in response to the articulation of the end effector relative to the elongate body in the first direction.
 2. The surgical loading unit according to claim 1, wherein the second segment is disposed proximally of the first segment.
 3. The surgical loading unit according to claim 1, wherein the second segment is configured to resist deformation as the second segment pivots in the second direction.
 4. The surgical loading unit according to claim 1, further comprising an elongate guide member pivotably supported in the distal portion of the elongate body and defining a longitudinally-extending channel, wherein the flexible knife bar is received in the channel of the elongate guide member.
 5. The surgical loading unit according to claim 4, wherein the second segment is slidably received in the channel of the elongate guide member.
 6. The surgical loading unit according to claim 4, wherein articulation of the end effector relative to the elongate body in the first direction effects movement of a distal portion of the elongate guide member in the second direction.
 7. The surgical loading unit according to claim 6, wherein the proximal portion of the end effector includes: a first wall that tapers proximally; and a second wall that tapers proximally such that the first and second walls cooperatively define a proximally-flaring cavity through which the first segment of the flexible knife bar extends.
 8. The surgical loading unit according to claim 7, wherein each of the first and second walls defines an arcuate side surface, the arcuate side surfaces being laterally spaced from one another.
 9. The surgical loading unit according to claim 7, wherein the first wall has a proximal portion configured to engage the flexible knife bar in response to the articulation of the end effector in the first direction to move the distal portion of the elongate guide member in the second direction, and the second wall has a proximal portion configured to engage the flexible knife bar in response to an articulation of the end effector in the second direction to move the distal portion of the elongate guide member in the first direction.
 10. The surgical loading unit according to claim 4, wherein the elongate guide member includes a proximal portion pivotably coupled to the elongate body, such that the elongate guide member is prevented from translating longitudinally relative to the elongate body.
 11. The surgical loading unit according to claim 4, further comprising another elongate guide member defining a longitudinally-extending channel, the flexible knife bar including: a first knife bar shaft extending through the channel of the elongate guide member; and a second knife bar shaft coupled to and extending parallel with the first knife bar shaft, the second knife bar shaft extending through the channel of the another elongate guide member.
 12. The surgical loading unit according to claim 11, further comprising a support structure disposed between the first and second knife bar shafts of the flexible knife bar, the support structure including: a top surface on which the elongate guide member is supported; and a bottom surface on which the another elongate guide member is supported.
 13. The surgical loading unit according to claim 1, further comprising a pair of blow-out plates extending along opposite sides of the flexible knife bar, wherein in response to the end effector articulating, the first blow-out plate is configured to slide relative to the elongate guide member in a first axial direction and the second blow-out plate is configured to slide relative to the elongate guide member in a second axial direction.
 14. The surgical loading unit according to claim 1, further comprising an articulation assembly for effecting articulation of the end effector, the articulation assembly including: an elongated drive nut disposed in the distal portion of the elongate body; an elongated drive screw disposed in the distal portion of the elongate body and threadingly coupled to the drive nut; and an articulation link having a proximal portion pivotably coupled to a distal portion of the drive screw or the drive nut, and a distal portion pivotably coupled to the proximal portion of the end effector.
 15. A surgical instrument, comprising: an elongate body; an end effector having a proximal portion pivotably coupled to a distal portion of the elongate body; an elongate guide member pivotably supported in the distal portion of the elongate body and defining a longitudinally-extending channel; and a flexible knife bar extending through the channel of the elongate guide member, the knife bar configured to move through the channel of the elongate guide member, wherein the flexible knife bar has a distal segment and a proximal segment, wherein the distal segment of the flexible knife bar is configured to curve in a first direction in response to an articulation of the end effector relative to the elongate body in the first direction, and the proximal segment of the flexible knife bar is configured to pivot in a second direction, opposite the first direction, in response to the articulation of the end effector relative to the elongate body in the first direction.
 16. The surgical instrument according to claim 15, wherein the elongate guide member has a distal portion, and wherein articulation of the end effector relative to the elongate body in the first direction effects movement of the distal portion of the elongate guide member in the second direction.
 17. The surgical instrument according to claim 15, wherein the proximal segment of the flexible knife bar is slidably received in the channel of the elongate guide member, the elongate guide member being configured to resist deformation of the proximal segment of the flexible knife bar as the proximal segment of the flexible knife bar pivots.
 18. The surgical instrument according to claim 15, further comprising: another elongated guide member defining a longitudinally-extending channel, the flexible knife bar including a first knife bar shaft extending through the channel of the elongate guide member, and a second knife bar shaft coupled to and extending parallel with the first knife bar shaft, the second knife bar shaft extending through the channel of the another elongate guide member; and a support structure disposed between the first and second knife bar shafts of the flexible knife bar, the support structure including: a top surface on which the elongate guide member is supported; and a bottom surface on which the another elongate guide member is supported.
 19. The surgical instrument according to claim 15, further comprising an articulation assembly for effecting articulation of the end effector, the articulation assembly including: an elongated drive nut disposed in the distal portion of the elongate body; an elongated drive screw disposed in the distal portion of the elongate body and threadingly coupled to the drive nut; and an articulation link having a proximal portion pivotably coupled to a distal portion of the drive screw or the drive nut, and a distal portion pivotably coupled to the proximal portion of the end effector.
 20. A surgical instrument, comprising: an elongate body; an end effector having a proximal portion pivotably coupled to a distal portion of the elongate body; an elongate guide member pivotably supported in the distal portion of the elongate body and defining a longitudinally-extending channel; a flexible knife bar extending through the channel of the elongate guide member, the knife bar configured to move through the channel of the elongate guide member; and an articulation assembly for effecting articulation of the end effector, the articulation assembly including: an elongated drive nut disposed in the distal portion of the elongate body; an elongated drive screw disposed in the distal portion of the elongate body and threadingly coupled to the drive nut; and an articulation link having a proximal portion pivotably coupled to a distal portion of the drive screw or the drive nut, and a distal portion pivotably coupled to the proximal portion of the end effector. 